HVACopediaGoodman-Amana-Daikin · Furnace · Ignition
Gas heat call, first and second stage
What happens, in order
- Thermostat closes W1; control gets 24 V on W1 and runs its self-check
- Control checks the limit switch is closed and the pressure switch circuit is open
- Gas valve circuit check relay state and voltage at the valve
- Inducer energizes; pre-purge begins once the low-fire pressure switch closes
- Igniter energizes and warms up
- Gas valve opens; igniter turns off as soon as flame is sensed
- Indoor blower starts on heat speed 30 s later
- With a single-stage thermostat the furnace moves to second stage by a fixed timer or auto mode (installer menu)
- W2 call inducer goes to high speed, closure of the high-fire pressure switch opens the high-fire gas valve stage and the blower moves to 2nd stage speed
- No flame control retries; after 3 tries in one call it locks out and shows E0
- Thermostat satisfied valve closes, inducer runs 15 s post-purge, blower runs the off delay (default 90 s)
Timings and thresholds
| Item | Value |
|---|---|
| Trial for ignition | 4 s |
| Blower on delay | 30 s |
| Post-purge | 15 s |
| Blower off delay | 90 s default, 30 to 180 s |
| Ignition tries per call | 3 (retries), then lockout |
| Lockout auto reset | 1 hour |
Codes you may see during this
Applies to: Goodman GC9C96, GM9C96, AC9C96, AM9C96; Daikin DR96TN, DD96TN; Goodman/Amana GM9S96 family (single-stage models skip the second-stage steps)
Models
More Goodman-Amana-Daikin furnace sequences
- Gas heat call and shutdown · Ignition
- Two-stage gas heat call with ramped blower · Heating
- Cooling and fan only · Cooling
- Cooling and fan only · Cooling
- Low and second stage cooling with the furnace blower · Cooling
Take it to the job
Sequences of operation, error codes and tips work offline in the HVACopedia app.
Source: Goodman GM9C96 / GC9C96 service RS6612020r1, Gas Heat Sequence of Operation; Daikin DR96TN / DD96TN service RSD6612304; Goodman GM9S92 / GM9S96 service RS6612022r1. Written in our own words; timings can differ by model and software version, so check the manual for your exact unit.
For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.